(a) Field of the Invention
The present invention relates generally to flat panel displays. More particularly, the present invention relates to an electrophoretic display and a method of driving the electrophoretic display.
(b) Description of the Related Art
Electrophoretic displays (“EPDs”) are flat panel displays that are commonly used in applications such as electronic books. Electrophoretic displays can be classified into vertical electric field type electrophoretic displays and horizontal electric field type electrophoretic displays.
A vertical electric field type electrophoretic display typically includes two display panels having field generating electrodes, and an electric ink layer that is interposed between the two display panels. The ink includes microcapsules containing white or black positive charged particles and black or white negative charged particles.
A horizontal electric field type electrophoretic display includes a display panel having two field generating electrodes, an opposite display panel, and an ink layer that is interposed between the display panel and the opposite display panel. The ink contains white or black positive particles or negative particles.
The horizontal electric field electrophoretic display displays images by applying a voltage to the two field generating electrodes, thus generating a horizontal electric field that causes white and black charged particles to move toward those electrodes that have the same polarity.
In comparison with liquid crystal displays, electrophoretic displays have higher reflectivity and contrast ratio, and project images that are not as dependent on viewing angle. These characteristics allow the electrophoretic displays to project images that, to many readers, resemble books. Further, black and white color bi-stable characteristics of the electrophoretic displays enable images to be maintained even without continuous application of a voltage, thus saving power consumption.
Electrophoretic displays are often cheaper than liquid crystal displays, as they do not require a polarizer, alignment layer, or liquid crystal.
Electrophoretic displays typically use red, green, and blue charged particles, or red, green, and blue color filters to display colors. However, since electrophoretic displays are reflective display devices, electrophoretic displays cannot display a white color with only red, green, and blue charged particles, or red, green, and blue color filters.
To address this issue, electrophoretic displays often include white pixels without a color filter or with white charged particles. However, the use of white filters or particles yields a smaller color gamut. Further, because a white pixel corresponds to a quarter of a dot, white pixels cannot provide sufficiently bright white color and as a consequence contrast ratio is lowered.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that is not known in the prior art.